Can High Uric Acid Levels Cause Kidney Stones?

Uric acid (UA) stones comprise 10% to 15% of all kidney stone cases. And the majority of patients suffering from UA stones, around 79%, are men, mainly in the 60 to 65 age group.

Many people associate high uric acid levels in the urine (hyperuricosuria) as the primary triggering factor for this type to form. However, this is entirely not the case. We will dive into this misconception in the following sections, so read on.

WHAT IS HYPERURICOSURIA?

Hyperuricosuria refers to the increased urinary excretion of uric acid and sodium urate. It is generally defined as excretion levels above 800 mg/day in men and 750 mg/day in women.

Urinary uric acid is assessed using a 24-hour urine test. What’s considered normal can vary depending on the lab and the units they use, but generally, having 250 to 750 mg of uric acid in your urine over 24 hours is considered normal. However, “optimal” levels are no more than 600 mg/day. Levels over this may signify excess uric acid in your blood or impaired regulation by your kidney.

CAUSES OF HYPERURICOSURIA

There are different causes of hyperuricosuria. Let’s delve into the various factors that can trigger this condition.

Metabolic dysfunction due to poor diet

If you ask doctors what is possibly causing your elevated uric acid levels, they would surely blame purine-rich foods like meat. However, this is not true. The actual cause of hyperuricosuria is impaired metabolic health.

For instance, 90% of uric acid filtered by the kidneys is reabsorbed into the proximal convoluted tubule (reabsorption and secretion unit). That means only 10% is left in the urine. However, when a person has proximal tubule dysfunction, more uric acid can end up in the urine.

Also, insulin resistance, another metabolic condition, can lead to more synthesis of purines in the liver. Purines are precursors of uric acid.

Now, the leading cause of impaired gut health is diet, but not protein-rich foods as Western medicine suggests. Instead, watch out for the following:

• Vegetable oils and seed oils
• Carbohydrate-rich foods
• Added sugars
• Processed foods

You should stay away from these foods because they fire up your cravings, resulting in more intake and eventually ruining your metabolic health.

Many processed foods are high in sugar and unhealthy fats. These ingredients can stimulate the release of dopamine, a neurotransmitter associated with pleasure and reward, in the brain. Over time, the brain can become desensitized to these signals, leading to cravings for more intense flavors and sensations.

Also, highly processed carbohydrates like white flour and refined grains are rapidly digested in the body. That’s because glucose is stored in the liver and muscles (in the form of glycogen), but these stores are relatively limited. When these stores are depleted, the body will signal for insufficiency. This can lead to cravings for more carbohydrates as the body seeks to maintain stable blood sugar levels. Over time, this can result in insulin resistance and diabetes.

Furthermore, the Western diet is characterized by an overconsumption of omega-6 fatty acids, mainly in the form of linoleic acid. Linoleic acid is commonly found in many processed and fried foods, often in the form of vegetable oils, which are used for cooking and food preparation. High consumption of processed and fried foods is associated with several health issues, including gut inflammation and obesity.

Again, some direct results of these conditions are uric acid overproduction and impaired kidney reabsorption.

Underlying disorders

Disorders associated with cellular breakdown can also result in high uric acid levels. That’s because certain cells contain nucleic acid. Nucleic acids contain purines, which break down into uric acid.

These disorders include the following:

• Tumor lysis syndrome – A potentially life-threatening complication that can occur after treating certain cancers, particularly rapidly growing or highly sensitive ones.
• Myeloproliferative disorders – A rare blood disorder characterized by the excessive production of blood cells (particularly white blood cells).
• Hemolytic anemia – A type of anemia characterized by the premature destruction (hemolysis) of red blood cells.

Overall, these potentiall contributing disorders are pretty rare, though.

Medications

Certain medications can also trigger hyperuricosuria, such as follows:

• Atorvastatin – Used to lower elevated cholesterol levels in the blood, specifically low-density lipoprotein (LDL) cholesterol, often referred to as “bad” cholesterol.
• Amlodipine – Primarily used to treat high blood pressure (hypertension) and certain types of chest pain (angina).
• Losartan – Helps treat high blood pressure and can also be prescribed to protect the kidneys in people with type 2 diabetes.
• Probenecid – A medication used to treat gout and prevent gout attacks.
• Salicylates – Salicylates are a group of drugs that include aspirin. They are used for various purposes, including pain relief, reducing fever, and as anti-inflammatory agents.

Congenital conditions

Another potential cause of hyperuricosuria is congenital conditions. However, they are uncommon, affecting roughly 1 in 10,000 to 100,000 live births.

• Lesch-Nyhan Syndrome – A rare and severe genetic disorder characterized by neurological and behavioral abnormalities and overproduction of uric acid.
• Von Gierke Disease (Glycogen Storage Disease Type I) – A rare inherited metabolic disorder that affects how the body stores and uses glycogen, a form of stored glucose.
• Type 1 Collagen Storage Disease (Osteogenesis Imperfecta) – Characterized by fragile bones that are prone to fractures and other connective tissue and skeletal abnormalities.
• Hartnup Disease – A rare genetic disorder that affects the absorption of certain amino acids, particularly tryptophan, in the intestines and kidneys.
• Wilson’s Disease – A disorder associated with abnormal accumulation of copper in the body, primarily in the liver and brain.
• Familial Hypouricemic Hyperuricosuria (“Renal Uric Acid Leak”) and URAT1 Mutations – This condition is characterized by defects in the reabsorption of uric acid by the kidneys.
• Sickle Cell Disease and other hemolytic anemias (due to high cell turnover) – Affects hemoglobin, the oxygen-carrying protein in red blood cells.

URIC ACID AND KIDNEY STONES

Aside from UA stones, uric acid is also believed to be a risk factor for Calcium Oxalate (CaOx) stones. However, let’s debunk the misconception surrounding both stone types.

Uric Acid Stones

Most uric acid stone-formers don’t necessarily produce too much uric acid. Instead, their urine is more acidic. When your urine is too acidic (pH <5.5), it’s more likely to form uric acid crystals because it doesn’t dissolve below 5.5 pH.

Urine pH is the major risk factor for UA stones. Four studies have found that every patient with uric acid stones had a urine pH of less than 6. Even when urinary uric acid is normal, a low urinary pH leads to the formation of UA stones.

Similarly, decreased ammonia production (an alkaline ion) lowers urine pH among patients with type 2 diabetes, metabolic syndrome, and chronic diarrhea. This is the leading cause of uric acid stones in these groups.

Thus, what’s important to understand is that the ability of your urine to dissolve uric acid depends on two main things: the acidity of your urine (pH) and how much urine you produce.

Calcium Oxalate Stones

Hyperuricosuria is thought to be a risk factor for calcium stones too. The reason is that uric acid in the urine is believed to decrease the solubility of calcium-oxalate, a phenomenon known as “salting out.”

While clinical research has shown that uric acid can cause calcium oxalate to salt out, not one study was able to prove that a protein-rich diet will cause calcium oxalate stones. In fact, one large study didn’t find a clear link between the two.

HOW TO PREVENT HYPERURICOSURIA

As mentioned previously, hyperuricosuria is mainly a result of metabolic dysfunction rather than purine-rich foods like meat and animal fats. That means you must fix your metabolic health to have normal uric acid regulation in the intestines, liver, and kidneys.

Fixing your metabolism involves shifting from diets abundant in vegetables, carbohydrates, and processed foods, such as the Western diet, towards animal-based. Contrary to what mainstream media might say, animal-based nutrition is way healthier and safer for kidney stone-sufferers. This is the most genius way to solve your gut issues, not just to prevent kidney stones but also to reclaim your overall health.

If you want to dive deeper on the right diet for kidney stones, check out our Coaching Program. This will give you an opportunity to have all your questions answered and be appropriately guided on your diet.

REFERENCES

1. Hyperuricosuria – Science Direct

2. Hyperuricosuria – StatPearls

3. Uric Acid Nephrolithiasis

4. Uric Acid Stones and Hyperuricosuria

5. Uric acid urine test

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